Problem: Solve for $x$ and $y$ using substitution. ${2x+y = -4}$ ${x = -2y-11}$
Since $x$ has already been solved for, substitute $-2y-11$ for $x$ in the first equation. ${2}{(-2y-11)}{+ y = -4}$ Simplify and solve for $y$ $-4y-22 + y = -4$ $-3y-22 = -4$ $-3y-22{+22} = -4{+22}$ $-3y = 18$ $\dfrac{-3y}{{-3}} = \dfrac{18}{{-3}}$ ${y = -6}$ Now that you know ${y = -6}$ , plug it back into $\thinspace {x = -2y-11}\thinspace$ to find $x$ ${x = -2}{(-6)}{ - 11}$ $x = 12 - 11$ ${x = 1}$ You can also plug ${y = -6}$ into $\thinspace {2x+y = -4}\thinspace$ and get the same answer for $x$ : ${2x + }{(-6)}{= -4}$ ${x = 1}$